Precipitation-strengthened copper alloy and application thereof

Abstract

The invention is a precipitation-strengthened copper alloy, including the following components in percentage by weight: 80 wt %-95 wt % of Cu, 0.05 wt %-4.0 wt % of Sn, 0.01 wt %-3.0 wt % of Ni, 0.01 wt %-1.0 wt % of Si, and the balance of Zn and unavoidable impurities. According to the invention, the comprehensive performance of the alloy is improved by solution strengthening and precipitation strengthening; while the strength of the matrix is improved, the electrical conductivity of the alloy is hardly affected, the bending workability meets the requirements, and the stress relaxation resistance comparable to that of tin phosphor bronze is achieved. The comprehensive performance of the alloy of the invention is superior to that of the tin phosphor bronze C51900. Furthermore, the alloy of the invention is low in raw material cost, has obvious advantages in welding and plating.

Description

BACKGROUNDTechnical Field[0001]The invention relates to the technical field of copper alloys, in particular to a precipitation-strengthened copper alloy with high strength and application thereof.Description of Related Art[0002]In recent years, with the development of the electronic and electrical industries, various mechanical and electrical wirings have become complicated and highly integrated, and the requirements for further lightweighting and reliability of electrical and electronic components such as connectors, relays, and switches are drawing more and more attentions. In particular, connectors, sockets and the like used in tablet computers and mobile phones are required to be space-saving and high-performance at the same time. The thickness of copper alloy strips is required to be thinner, and higher requirements are put on the elasticity and reliability of copper alloys. Specifically, the miniaturization and thinning require improvement in the strength and elasticity of the...

AI Technical Summary

Benefits of technology

The invention is an alloy that improves the strength of copper alloy while maintaining good electrical conductivity. It uses elements like nitrogen, silicon, and antimony to solution strengthen the alloy and form a strong matrix. The alloy also has superior bending workability and resistance to stress relaxation. It can be used to solve the problem of waste and promote recycling of various cracks. Overall, the alloy has superior performance compared to tin phosphor bronze and offers benefits in strength, cost savings, and environmental friendliness.

Problems solved by technology

In recent years, with the development of the electronic and electrical industries, various mechanical and electrical wirings have become complicated and highly integrated, and the requirements for further lightweighting and reliability of electrical and electronic components such as connectors, relays, and switches are drawing more and more attentions.

Brass C28000 can meet the requirements of common connectors and terminals for material properties, but especially in the field where high stress relaxation resistance is required, the lack of comprehensive performance of brass is very obvious.

Sn contained in phosphor bronze has a solution strengthening effect, and moreover, cold deformation hardening makes phosphor bronze have higher strength; however, Sn affects the electrical conductivity of phosphor bronze, and the electrical conductivity of phosphor bronze is generally below 20% IACS; in addition, the price of Sn is relatively high.

Therefore, the application of phosphor bronze is limited to some degree.

Beryllium contained in beryllium bronze is toxic, and beryllium bronze is expensive and is generally only used in certain fields where high elasticity and strength are required.

As an aging precipitation strengthened alloy, the copper-nickel-silicon alloy is developed to replace beryllium bronze, but due to high processing cost, the copper-nickel-silicon alloy is usually applied to the field of high-end connectors which have high requirements for strength and electrical conductivity.

If the Zn content is too low, the effect of solution strengthening is not significant, and the recycling of brass scrap is limited; and if the Zn content is too high, the electrical conductivity, bending workability and stress corrosion resistance of the alloy are lowered.

If the Ni content is less than 0.01 wt %, the strength of the alloy is not improved obviously; when the Ni content exceeds 3.0 wt %, the NiSi phase cannot be completely precipitated, thereby affecting the electrical conductivity of the alloy and causing a disadvantageous effect for bending workability.

Conventional brass increases the strength of the matrix by solution strengthening, so its strength is limited.

The inventors of the present application have found through extensive experiments that the finer and the more dispersive the precipitates are, the higher the strength of the alloy is; if precipitates are coarse, a weak interface is easily generated, which causes cracking when the alloy strip is bent; if the precipitates are too segregated, local stress concentration will be caused easily, which also causes cracking when the alloy strip is bent.

When the Fe content is too large, the electrical conductivity of the alloy is adversely affected.

However, if excess P is added, the electrical conductivity of the alloy will be lowered seriously, and a low-melting eutectic phase Cu3P is easily formed, causing the alloy to be cracked during hot rolling.

When the Cr content exceeds 1.5 wt %, the electrical conductivity and the workability of the alloy are deteriorated.

When the Mn content is less than 0.001 wt %, the above-mentioned effects cannot be achieved, and when the Mn content exceeds 0.8 wt %, the electrical conductivity and the elastic modulus will be reduced seriously, and thus the use requirements of the alloy cannot be reached.

If the deformation is too small, it is not conducive to the completion of recrystallization in the post-aging structure, which is disadvantageous for the bending process of the plate strip.

However, if the aging temperature is too high, the overaging problem is likely to occur, which is not conducive to the strength increase of the alloy.

Applying cold deformation to the alloy after aging is favorable for the further improvement of the strength of the strip, but the deformation should not be too large, and too large deformation may cause the recrystallized structure to be completely broken, which is not conducive to the bending workability of the strip.

Images